DURING THE 1950s and ’60s era of urban renewal, Boston, like many cities, destroyed old and historic buildings, replacing them with new, modern structures that embodied the spirit of an age of prosperity and limitless growth.
The impulse to tear down and build anew was rooted in the belief that man had transcended the limits of the natural environment. After all, this was an era of plentiful and cheap energy, especially oil, when we shunned the frugality of our forebears and embraced the throw-away society. The cultural shift was reflected in the design of modern buildings, which relied on energy-intensive systems of lighting and climate control.
Only in hindsight did we see how reckless we had been. Books like Jane Holtz Kay’s “Lost Boston’’ chronicled the destruction of our cultural and architectural heritage. The architectural and historical landscape of Boston and other historic cities was spared the full brunt of urban renewal by a powerful countermovement of historic preservation that emerged in the 1970s and helped lessen the destruction.
Ironically, there is now a risk that this same impulse to tear down and build anew could reemerge from quite the opposite source: sustainability. Although premised on an awareness of ecological limits and the finiteness of natural resources, sustainability, as it applies to urban environments, is focused to a large extent on new design and construction. Green buildings are overwhelmingly considered new buildings. Old buildings are thought of as inefficient and wasteful. There is a danger that urban planners, community groups, and elected officials might come to see tearing down the old and replacing it with the new as the path to a more sustainable future.
It would be tragic, not to mention terribly wasteful, if this is the road we follow. Many existing buildings, especially those built before World War II, embody environmental and energy-conscious design. Of course these buildings were not designed with the fate of the planet in mind. But they were built in an age predating modern lighting and HVAC systems, before cheap oil created the illusion of a world without limits. They were frugal in design and use of resources - the very antecedent of our modern concept of sustainability.
If you look around Boston, you will find old buildings with large vertical windows that allow sunlight to penetrate their interior spaces. Before air conditioning, many buildings featured high ceilings and natural ventilation to help keep workers cool. In fact, according to an article by a director of the Association for Preservation Technology International, buildings constructed before 1920 on average consume less energy per square foot than those built in any decade since.
Like any product, buildings embody energy and materials that were spent in their production. Demolition of existing buildings produces waste while new construction requires that we expend new energy and resources. Reuse of existing buildings will often produce the least environmental impact.
Many existing buildings, especially those of pre-World War II vintage, are ripe for improvements that enhance their energy efficiency and reduce their environmental impact. Replacing old mechanical systems for heating, air conditioning, and ventilation with new state-of-the art systems can deliver enormous energy savings. Adding insulation alone can produce energy savings on the order of 10 times the cost of installation.
There are encouraging signs. Cambridge City Hall Annex, built in 1871, achieved LEED (Leadership in Energy and Environmental Design) Gold in 2006, the oldest building in the world to attain that standard. The current version of LEED applies a life-cycle assessment that assigns points for retention of existing buildings.
There are real challenges to greening existing buildings, especially those structures built in the three decades after World War II, which are the real “gas guzzlers.’’ More can be done at a policy level to encourage reuse, including establishment of tax credits of the kinds that were instrumental in the adaptive reuse of buildings such as the old mill buildings in cities like Lawrence, Lowell, and Lynn.
But Boston, as a city deeply rooted in the past but a leader in energy-efficient technology, is ideally suited to lead a new revolution in design: the reconciliation of preservation, reuse, and sustainability.
Charles N. Tseckares is a founding principal of the Boston architectural firm, CBT, and past president of the Boston Society of Architects. 
